1. Field of the Invention
The present invention relates to a water detection and alert system for detecting the presence of water and leaks from appliances in homes or apartments by employing an extended sensing device that may be conveniently disposed in the form of strips in areas of a home or apartment where water would be expected to accumulate in the event of a leak from an appliance or from cracks or faults in walls which could be expected to seep water. More particularly, the invention pertains to a water detection device employing a resistive sensing system for detecting water in low, shallow pools which as a result of the slowness of the water leak in conjunction to the absorbency of the substrate has the potential of creating serious property damage. The invention employs a sensor system capable of customized disposition and electronic detection and alarm circuit that is compatible with existing fire alarm circuits and a cabinet housing which is mountable at a source removed from the extended sensor.
2. Description of the Prior Art
The prior art includes a variety of patents pertaining to water leak detection devices which are designed to detect water and automatically shut-off an appliance or provide an alarm in the event water is detected in the vicinity of a water using appliance. A significant amount of this prior art utilizes sensing devices of various types and configurations which are not extended or in other words, are confined to a particular area or locality where water will be assumed to collect in the event of a leak. Representative of this prior art are patents such as Hatfield, U.S. Pat. No. 4,020,478, Jui-Cheng Hsu, U.S. Pat. No. 3,562,731, Uhlig, U.S. Pat. No. 3,200,388, and Brown, U.S. Pat. No. 3,770,002.
In such prior art water detection devices, the efficiency of the detection device is severly limited by the fact that if the water does not reach the water sensor, the alarm will not be sounded even though a slow leak may cause substantial damage since the rate at which the water enters a room may be compensated by the absorption of the water into rugs, cracks between the boards in the wooded floor, and as a result, cause substantial damage to the foundation of a house or to the ceiling and floors below in the case of an apartment.
The prior art primarily utilizes capacitive sensing systems to detect water from leaking appliances or other sources. Illustrative of prior art patents utilizing capacitive circuits for water detection systems are Ferrigno, U.S. Pat. No. 3,221,317, Brown, U.S. Pat No. 3,770,002, and Gustafson, U.S. Pat. No. 3,824,460. The utilization of capacitive water detection systems requires an oscillator in order to detect capacitive changes, these oscillators generate by their nature, radiated emissions which may effect surrounding equipment if not shielded. Furthermore, the capacitive system of sensing water or leaks is cumbersome in comparison with the present invention and therefore electrical radiation is not generated nor is a shield required for the present invention and the present system utilizing resistive sensor which allows the present system to interface with existing fire alarm detection integrated circuits.
Gustafson, U.S. Pat. No. 3,824,460 employs a capacitive sensing system which utilizes a sensor that may be disposed in an area or room in a configuration which like the present invention does not require the disposition of the sensor at one particular location. The prior art patent Gustafson however, represents a capacitive sensing system which requires water to cover specific areas of the sensing wire in order to detect water and furthermore does not detect small amounts of water that may travel along the sides of the water sensing device, see for example FIG. 2. Furthermore, the capacitive sensing system of the prior art does not interface with existing fire alarm detection integrated circuits and requires an adjustment of the detection device upon the addition of additional lengths of the sensor strip. The sensor strip, furthermore, cannot be used to bend around corners without losing its capacity to detect water.
The present invention may be distinguished from such prior art water detection devices in a number of significant respects. Perhaps the most distinguishing feature of the present invention over the prior art resides in the utilization of a resistive sensing system along with a sensor strip that can be utilized to bend around corners and encircle appliances while being quickly and easily installed to provide a sensitive leak detection system having an improved capacity for the detection of water. Unlike the prior art patents utilizing a single sensor and prior art patents using an extended sensor, the extended sensor of the present invention can be designed to bend around corners without losing its capability of detecting water.
The present sensor can be formed on an ultra-thin plastic tape with an adhesive backing which can be installed on the floor, wall areas and other places which are susceptible to the leakage of water. The thickness of the sensor which may be a thin mylar strip, and may be only a few thousandths of an inch thick, allows small streams of water to be detected by the sensor device and as a result, provides a means for correcting the leakage of water by the sounding of an alarm or in an alternative embodiment, the shutting off of the water supply system or the appliance.
Further, unlike the prior art, the present invention provides an efficient and economically manufactured water detection system that does not require adjustment and recalibration of the capacitive sensing circuitry upon the addition of additional strips or lengths of sensor tape. In addition, the prior art capacitive sensing systems may lose much of their effectiveness in the calibration of the system or the failure to recalibrate upon the addition of subsequent lengths of sensor. Since the present invention is based upon a resistive system, calibration is not required in order to provide an accurate and efficient water alert and detection system. Furthermore, the integration of the present resistor sensor to existing fire alarm detection equipment and burglar alarm detection equipment provides a means for the integration of one or more existing systems to a single alarm system. These advantages of the present invention are inherent in the present combination of elements utilized to provide a superior yet economically produced water leak detection system.